Why the CIP wire cannot be inserted into the machine: oxidation, heating and fire

  • Dec 14, 2020
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What is SIP? Self-supporting insulated wire, which is used to transmit electricity to the consumer directly from the transformer substation. It has a lot of brands (SIP-1, SIP-2, SIP-3, etc.), each of which differs from the rest in certain design features. But what happens if you connect the SIP directly to the machine, what are the consequences?

What happens if you connect the self-supporting insulated wire directly to the machine?

SIP is a wire, the current-carrying core of which is made of aluminum. And the terminal clip of any circuit breaker is made of more practical copper. If aluminum and copper can be combined, then only for a short time. But why?

Aluminum is a lightweight yet durable metal. It can be bent in every possible way, and the conductivity is not too different from copper, despite the fact that the cost is much lower. But aluminum has one serious drawback - it oxidizes too quickly. The film that appears on its surface under the influence of oxygen is an excellent dielectric, and just a well-tightened contact will not help here.

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Figure 1: Cable SIP-5ng
Figure 1: Cable SIP-5ng

Even if the twisting of aluminum and copper wires is very high quality, the contacts will burn out soon. The oxide film will become additional resistance between the two metals, causing excessive heat. And the rapid rise in temperature will do the rest. What consequences? Basically, a burnt out machine gun, much worse - a fire.

Piercing clamp is the best solution

But still, it is somehow necessary to supply electricity to the house and the most correct solution in this situation will be to use a piercing branch clamp for self-supporting insulated wire.

What are the advantages of this device:

  • A large number of different models.
  • High dielectric characteristics of the housing.
  • Long service life.
  • Affordable pricing policy.
Figure 2: Piercing branch clamp for self-supporting insulated wire.

For example, the cost of a French branch clamp for self-supporting insulated wire is a little over three and a half dollars. Such a device is capable of piercing the main wire with a cross section of up to 95 mm2, and the conductor that goes to the consumer - up to 10 mm2. The design of the clamp is such that no external part is energized even after puncture. Convenient, fast and reliable.

WAGO terminals - for small cross-sections

The self-supporting insulated wire has a fairly large section - 10 mm2 or more. And if it is necessary to make an aluminum / copper connection on smaller conductors. Then the German WAGO self-clamping terminal blocks are ideal.

There is a special model in WAGO products, which is designed for high-quality and durable connection of aluminum and copper conductors. Inside, the terminal is filled with a special paste, which does not allow an oxide film to appear on the surface of the aluminum core, therefore, the quality of contact is not lost.

Figure 3: WAGO terminal for connecting copper and aluminum conductors

In addition, WAGO is self-clamping and does not require periodic check of the contact reliability. The most important thing when choosing is not to run into a cheap Chinese fake.